first time carb work = nightmare

[Scott_mi]

First time doing any work an any kind of carb and it's turning into a nightmare. Anyone got some advice, tips or suggestions?

It's on a 7hp Tecumseh engine believe it's this (Tecumseh H70-130210K)
Make a long story short I got new needle, seat, and nut/jet? but I keep getting gas overflowing the carb throat still.

Don't have gas inside the float. Placed the float in gas looking for air bubbles and nothing. If I turn the carb upside down and blow into the gas inlet opening, I can't pass any air through so seems the needle and seat is sealing good.

I'm not sure what else to consider or to try next. Wondering if the float can just "lose" it's buoyancy even though it's not getting gas inside? It does seem to sit lower in a bowl of gas on one side (hinge side) than it does the other. That may just be the weight? Doesn't seem that the float is sticking or binding in it's movement when I have it open, unless it's hitting the side of the bowl once it's all installed.

Any other possibility's I'm missing that need to be considered?

Float sticking/hitting bowl.
Float not floating high enough to seat the needle
Needle not seating completely

 

[The motor guy]

it's possible. I've never had a float sink though. I have had the gas pouring out of the intake though after cleaning and putting everything back together. It's possible it's hung up. I would just take the bowl of and move the needle and float up and down and then put the bowl back on. I've even had this problem on brand new engines.

 

[Cujet]

The trick to working on carbs is to REALLY understand each and every small detail properly. The problem is, people think a carb is a needle/seat/float/jet and idle circuit. There is much more to the design.

Yes, floats can sink. But, more than that, you can place your float in a cup of gas and see what it does. Observe it's droop, it's action on the needle, the wear on the hinge pin, etc. Every detail. Each passage must be understood, then observed as "clean" via proper flow testing.

 

[NHGUY]

I had an 8hp Tecumseh,ran and started horribly,replaced the carb with a new Walbro.Still started when it wanted to and ran bad.Removed it,installed a new Briggs and never looked back.There's a reason why Tecumseh/Lauson Power Products is out of business.

 

[Joe72Mart]

Does it have the press in seat? Is it in the proper way?
Good youtube video on rebuilding:

 

[Scott_mi]

I've been fighting this part of yesterday and today. Done in about 15 times and I don't ever see or find anything when I open it up. I thought I found a solution when I seen a video about adjusting the float tab if it's sitting too high or too low. Adjusted it so it sat level when held upside down. Thought for sure that was gonna solve it but it did not.

Thanks for the video link. That's a similar carb to what I'm working with, and the same rebuild kit i'm using so it directly applies to my application. As far as the float, needle, and seat everything was done as shown in the video. I'll use his method of checking the spacing of the float with the drill bit see what I notice. If I don't end up with a fix, guess I'll try a new float and bowl and then after that guess I'll be paying shop rates.

 

[crainholio]

I've seen this on a roto-tiller carb where the bowl vent passage was clogged with dirt. It would initially start and run, then start leaking gas all over the place and flood out as if the float & needle wasn't closing.

 

[GreeCguy]

Originally Posted By: Cujet
The trick to working on carbs is to REALLY understand each and every small detail properly. The problem is, people think a carb is a needle/seat/float/jet and idle circuit. There is much more to the design.

Yes, floats can sink. But, more than that, you can place your float in a cup of gas and see what it does. Observe it's droop, it's action on the needle, the wear on the hinge pin, etc. Every detail. Each passage must be understood, then observed as "clean" via proper flow testing.


Very good wisdom here. All I can add is that obviously gasoline is running out of the carb for a reason. There has to be something that is either hanging the float or causing the float not to "float" properly. Or, it could be something is wrong with the needle valve. Could there be trash, dirt, debris between the needle valve and the seat so it doesn't seat properly. Could the pin that holds the float in place be worn or even installed incorrectly?

Does gasoline run out of the carb throat immediately after you add gas to the tank or turn on the valve, (assuming there is an inline valve)? If it does, that tells me something is wrong with the needle or seat or both. Just my humble opinion.

 

[Warstud]

One way of testing it.... is to take off the bowl and raise the float by hand to see the gas stops flowing. That should tell you if needle and seat are working properly.

 

[Donald]

How much is a new carb?

The original carb on my Kohler Courage engine was replaced by Kohler because of some defect where the seat was corroding. It was a known problem.

I saw another engine where the bowl had an indentation and could only go back with the indentation in one place. Turn it 30 degrees and it would jam the float assembly.

How old is the engine?

 

[jeepman3071]

Tecumseh carbs also give me nightmares sometimes. They can be a real pain. If the needle and seat don't fit together just right you will have the issues you are describing. I would try as others have mentioned to test the needle and float with the bowl off to see if it stops the flow of fuel.

Honestly, if it was me, I would just replace the carb. It saves you the headache and you know it will run right. I've had to do this on a few that wouldn't run right even after multiple cleanings and adjustments.

Here is the exact one for your machine (Tecumseh H70) on ebay for $35 shipped:

http://www.ebay.com/itm/CARBURETOR-TECUM...=item3a6aaf727a

 

[old1]

Go back and re-read what crainholio said. I am sure that is your problem. About 30 years ago I first stumbled on that problem, and I was pulling my hair out till I cleaned the bowl vent-- No more problem. Now I make sure to check with every rebuild.

 

[Merkava_4]

Originally Posted By: Scott_mi
Anyone got some advice, tips or suggestions?


Yes! Take the time to learn the theory of operation! Despite what most people think about carburetors, they're not that complicated. They operate on the basic physics principle of vacuum and pressure. They'll be a lot easier to repair if you know how they work!

 

[lars11]

check orientation of the dent in the bowl, also check the orientation of the little spring that holds the needle as the manual states that it should have one specific side toward engine.
The little rubber seat that the needle seats against will also have to have the right side up/down.
I had a slow leak and the culprit was the rubber seat. It did not have the flat side down against the needle.
Check that the float is not bent sideways or something too.

 

[bubbatime]

Originally Posted By: Donald
How much is a new carb?



DING DING DING!! We have a winner Bob!!

These carburetors are only $24-30, BRAND NEW, on eBay, depending on model needed. You probably spent almost that much or more, just on the rebuild kit. Not to mention the hours of soaking in carburetor cleaner and the aggravation that it doesn't run right. And having to take it apart again and try to fix it. Just buy a new carburetor. This is really a no brainer.

$27 on Amazon
http://www.amazon.com/TECUMSEH-632371-63...371A+carburetor

$30 on eBay
http://www.ebay.com/itm/NEW-TECUMSEH-632...=item19f32b2af4

$24 on Ebay
http://www.ebay.com/itm/like/141349785254?lpid=82

Yes they are aftermarket made in China carburetors, but I have used a ton of them and they work perfectly every time.

 

[Scott_mi]

I think.....I think it might just be fixed. Did multiple things so can't say specifically what the deal was but I did play around with the vent as was suggested. So thanks everyone for the help and thanks for the tips on checking the vent part. Not that I had any idea what or where this vent was but I found something on google that lead me to believe the vent was tied to the barb nipple where the primer bulb hose connect. Does that sound right? or did I just get lucky messing around various places with drill bits, small wires, and compressed air?

As i said earlier, this was my first time doing anything on a carb and up until this thread I have never seen anything in any text or videos that I've watched/read that mentioned anything about a vent. I guess this carbs vent may be part of where the primer hose connects and I didn't really do anything with that barb nipple before.

 

[yeehaw1960]

The vent in question on an older Tecumseh Carb is just a tiny hole on the side of the body of the carb. No reason you would ever see it if you weren't looking. Normally though, it doesn't make anything overflow unless the engine was running right before the overflow happened. Without the vent being open, the fuel would continue to syphon through the carb until the gas tank was empty.

 

[asand1]

Before installing the new seat, I will cut one end off a Q-tip, chuck it up in a cordless drill, and polish the needle bore using a bit of abrasive hand cleaner. This assures the needle won't stick.

 

[Scott_mi]

I seen that in one of my many video's I watched, but didn't try it. After my post that I got it working, I warmed it up and drained/refilled the oil and have been running it for a little every now and again. Haven't had any problems since. Just need to grease and lubricate some things and get 2 new tires and can rest easy knowing It should be all set.

To answer another question, my guess it that it's either 1985 or 1995 If I've been reading about Techumseh's engine date codes correctly and the years this certain model snow blower was available. Now that I got my first carb fix under my belt I can think about taking on my dads generator that wasn't running the smoothest last time he lost power.

 

[threeputtpar]

That looks to be an 85 judging by the smaller diameter gas cap. I think around 88 or 89 Tecumseh switched over to a larger diameter cap.

That one is in really good shape for 1985. I found a 1989 ST824 like it for my SIL and an 88 ST824 for my FIL because they are such good machines.

I found $25 tires with the aggressive tread at Northern Tool. You just have to special order them. Both machines I picked up for relatives needed one tire.